President Obama on Friday nominated Dartmouth College President Jim Yong Kim to head the World Bank, turning to a physician and public health expert to run an organization traditionally led by heavyweights from the world of finance or politics.

The choice surprised those who followed the administration’s search for someone to replace President Robert B. Zoellick when he leaves office in June. Kim’s lack of finance experience was cited as a particular concern for an agency that aims to strengthen private markets and build infrastructure — alongside the public health and social programs it underwrites in the poorer parts of the world.

But Kim’s nomination breaks new ground for an agency whose leadership has reflected a certain American patriarchy: The bank’s first 10 presidents have been white men drawn from the top echelons of the country’s boardrooms or government agencies. By tradition, the U.S. government chooses the World Bank chief.

Kim’s family moved from South Korea to Iowa when he was 5, and the young boy lived what Obama called a version of the American dream — quarterbacking his high school football team, attending the Ivy League’s Brown University, and earning a medical degree and doctorate in anthropology from Harvard.

Teased for being too smart by comedian Conan O’Brien at a Dartmouth commencement speech last year, Kim has been no ivory tower recluse. The 52-year-old designed field programs that brought tuberculosis medicine to the far reaches of Peru and other remote places, and ran a World Health Organization program to expand delivery of HIV drugs.

That in-the-field experience — and a penchant for pushing big organizations to change — made Kim an ideal nominee, Obama said at a Rose Garden ceremony that hinted at possible new directions for the bank. The World Bank provides development aid and loans for poor and still-developing countries, although its role in global finance has been shrinking in an age in which private money moves more freely, and emerging powers such as China and Brazil have little trouble borrowing.

A product of the post-World War II reconstruction of Europe, the bank’s roster of countries that qualify for development aid is expected to dwindle in coming years as nations progress — a perfect time, some say, for a reevaluation of what the bank can do best.

“It’s time for a development professional to lead the world’s largest development agency,” Obama said at the announcement as Kim, Secretary of State Hillary Rodham Clinton and Treasury Secretary Timothy F. Geithner, a Dartmouth graduate, stood beside him. “Ultimately, when a nation goes from poverty to prosperity, it makes the world stronger and more prosperous for everyone.”

“Jim has truly global experience. He has worked from Asia to Africa to the Americas, from capitals to small villages. His personal story exemplifies the great diversity to our country.”

Nominating a public health expert as well as the first Asian American for the post could counter frustration among developing countries over the United States’ historical hold on the World Bank presidency. Under a decades-old agreement, the United States — as the bank’s major contributor — names the president of the bank, while the major European nations appoint the head of the International Monetary Fund.

Kim will be the first American World Bank nominee to face competition for the job. Ni­ger­ian finance minister Ngozi Okonjo-Iweala has been nominated and is supported by a group of African nations. South American countries have nominated former Colombian finance minister Jose Antonio Ocampo. Under the bank’s procedures, if three or fewer people are nominated, each will be interviewed by the 25-member governing board. A decision on the new president is expected before upcoming bank meetings in mid-April.

After the White House ceremony, Kim attended a small lunch at the Treasury Department that included Washington-based development groups and analysts. Some of them said they worry that Kim’s experience has been too narrow for the breadth of issues the bank faces: how to best encourage private investment in poor or developing countries; how to balance a country’s energy demands with climate concerns; how to navigate the politics of heavily subsidized commodities, tame volatility in food prices or influence the policies of rising giants such as India.

“The World Bank has to be more than just another good aid agency,” said Nancy Birdsall, president of the Center for Global Development. “It has to take leadership on issues of pricing, markets, weak institutions . . . on the fact that a whole bunch of middle-income countries don’t look to the World Bank for money.”

Kim did not speak at the White House ceremony. In a letter to Dartmouth alumni and others, he called the bank “one of the most critical institutions fighting poverty and providing assistance to developing countries in the world today” and said he would accept Obama’s nomination.

Kim’s selection ends a search that was closely held among a handful of top White House staff members and seemed initially to focus on major political figures such as Clinton and former Treasury secretary Lawrence H. Summers. Administration officials offered few details of the search but said Obama interviewed several candidates with backgrounds in various fields and wanted someone who agreed with him that poverty alleviation should be the bank’s central goal.

Kim will immediately leave for an international “listening tour” to cement support among other countries, according to an administration official. The official said the White House was confident of broad support.

One other candidate for the job, Columbia University professor Jeffrey Sachs, withdrew from contention as he praised Obama’s choice.

Kim “is a superb nominee,” Sachs said, a “world-class development leader.” Sachs had campaigned openly for the job, arguing that the bank’s next leader should be a development expert rather than someone who had spent a career in finance.

Kim, Dartmouth’s leader since July 2009, has worked extensively on health issues in the developing world. He directed the department of HIV/AIDS at the World Health Organization and led the agency’s “3 by 5” initiative, which sought to treat 3 million new patients in developing countries with antiretroviral drugs by 2005. The goal was accomplished in 2007. He co-founded the global health organization Partners in Health and in 2003 received one of the MacArthur Foundation’s “genius” grants.

Before arriving at Dartmouth — and becoming the first Asian American to lead an Ivy League college — Kim held professorships at Harvard Medical School and the Harvard School of Public Health.